D. Thompson et al., FORAGING BEHAVIOR AND DIET OF LACTATING FEMALE SOUTHERN SEA LIONS (OTARIA-FLAVESCENS) IN THE FALKLAND ISLANDS, Journal of zoology, 246, 1998, pp. 135-146
This study investigated the foraging behaviour, diving behaviour, move
ments and diet of lactating southern sea lions in the Falkland Islands
. They appeared to be primarily nocturnal, benthic foragers hunting at
depths ranging from the surf line down to 250 m, and from just off th
eir breeding sites out to 45 km offshore. Occasional longer trips may
extend foraging ranges to over 150 km from breeding sites. Attendance
patterns suggest that Falklands' sea lions do not haulout simply to fe
ed their pups. Other factors such as predation and thermoregulation ma
y cause them to come ashore. When at sea they travelled at approximate
ly 1 ms(-1), slower than previous studies of otariids indicated. Absen
ce from the breeding site did not imply continuous foraging; all study
animals used remote haulout sites away from their pups. Repeated use
of the same areas and the short duration of foraging trips suggest tha
t they were able to catch enough food within a fairly small foraging r
ange. Data on diet support the suggestion that lactating sea lions are
mainly benthic foragers. They take a wide range of prey species. The
most common cephalopods were Loligo gahi, similar in size to those tak
en by the fishery. There is therefore potential for competition betwee
n the sea lion population and the Loligo trawl fishery. There was cons
iderable overlap between the diet of sea lions and those of Gentoo and
Magellanic penguins, which suggests that sea lions may compete with b
oth species.